High performance liquid chromatogaphic determination of mixtures of benzoic acid and sorbic acid and methyl paraben and propyl paraben in some soft drinks and pharmaceutical formulations

ABSTRACT

A rapid, specific and accurate reversed phase HPLC method was developed and validated for the determination of cited compounds in bulk powder samples and commercial pharmaceutical and food products. HPLC was performed with a Pecosphere C18 column "Perkin-Elmer" [33 x 4.6 mm, 3 mum] with a mobile phase of methanol water [60 40] for the determination of the two parabens with UV detection at lambda 255 nm and methanol-phosphate buffer pH 45 [8 92] for the determination of the two acids with UV detection at lambda 235 nm. The influence of pH of phosphate buffer and its ratio in mobile phase was discussed. The typical linear range extended from 1-10 mug/ml for methyl paraben, 1-12 mug/ml for propylparaben, 5-50 mug/ml for sorbic acid and 5-100 mug/ml for benzoic acid. The results were evaluated by a linear regression analysis: